So here's a little write up on how I'm attaching the shot cards to my shot gun. I use Dual Lock 400/250 combo. This gives the strength of the dual lock approximately 60 lbs of disengagement force for every 1 inch.
1. I clean the side of the receiver w/ rubbing alcohol to clean it from oils to ensure that the 3M Dual Lock adheres to the surface.
2. I then attatch a strip of 3M Dual Lock to the side of the receiver. I measure about 6 inches of the dual lock to the side of the receiver. I usually lay down the Dual Lock 400 on the side of the receiver. Allow for 30 minutes to fully adhere to the surface.
3. I then clean the back of the shot card w/ rubbing alcohol to clean it. Then apply the adhesive. Again, allow 30 minutes to adhere to the back of the shot card.
Overall length for the 4 shot shell holder is approximately 3 1/2 inches.